1. Field of the Invention
This invention relates in general to clocks and in particular to a calendar clock which shows the rotation of the earth through night and day; it shows the earth in shadow as half of the earth turns away from the sun's rays; it shows the month and day of the year and it shows the position of certain major cities as each city revolves through night and day. It also shows the position of the north pole, and it shows parts of the earth that lay between the equator and the Tropic of Capricorn. It also shows the 24 time zones that make up the earth's meridians.
2. Prior Art
It is well known that there are many devices for showing the earth's relationship to the sun and also to the time of day. Some of these are earth globes which are usually shown set at a 231/2.degree. tilt from the vertical. By shining a light on the globe's surface and rotating said globe, one can obtain a good idea of the earth's relationship to the sun and subsequently the time of day for specific places on the earth's surface. Unfortunately, it is rather difficult to carry a globe with you when you are traveling or carrying out business. Therefore it is my idea to combine a clock and a globe in a convenient package such as a wrist watch. This said watch will do all these functions above mentioned and more. My clock or watch is not limited however to just a wrist watch. It may be a wall mount, desk top or any other size watch or clock. My invention is a two dimensional solution to this problem. Students of astronomy, international businessmen, military personnel, travelers, pilots, and people in general would be interested in this clock or watch.
Other two dimensional "earth clocks" are listed below.
The D. W. Thompson "Geographical Clock Dial" U.S. Pat. No. 557,173, Mar. 31, 1896. This device uses a movable screen to show the earth's shadow and must be adjusted from time to time. The north pole (or south pole) is not adjusted for the earth's tilting axis. The clock is a twenty-four hour clock and runs in a counter clockwise direction making this device hard to read. There is no system for the days or months of the year.
The S. W. Boggs "Horological Instrument and Related Devices" U.S. Pat. No. 2,056,089, Sep. 29, 1936. This device uses a stationery earth disc instead of a rotating disc which makes it difficult to read. This device also uses a twenty-four hour clock in place of the more standard twelve hour clock. The north pole is not offset to make up for the tilt of the earth. There is no system to determine the months or seasons or the day of the year.